Occurrence of Potash-Bearing Strata (Sylvinite) in the Salina A-1 Evaporite in the Central Michigan Basin*

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1 Occurrence of Potash-Bearing Strata (Sylvinite) in the Salina A-1 Evaporite in the Central Michigan Basin* William B. Harrison, III 1 Search and Discovery Article #10652 (2014)** Posted October 13, 2014 *Adapted from oral presentation given at AAPG 43nd Eastern Section Meeting, London, Ontario, Canada, September 27-30, 2014 **AAPG 2014 Serial rights given by author. For all other rights contact author directly. 1 Michigan Geological Survey, Western Michigan University, Kalamazoo, MI (harrison@wmich.edu) Abstract Potash occurs in the deep, center of the Michigan basin and contained exclusively in the Salina A-1 Evaporite formation as Sylvinite in the middle or upper portions of the formation. The Potash occurs as Sylvite (in relatively pure beds as much as 30 feet thick or as Sylvite (KCl) intimately intermixed with Halite (NaCl) as Sylvinite. These deposits were first described by Dow Chemical Company scientists in the early 1970 s, based on samples from a core in Midland County and nearby well Gamma Ray logs. The Potash zones are located between 7,000 and 9,000 feet deep and occur in all or parts of 17 counties in the northern half of Michigan s Lower Peninsula. Commercial Potash mining in Michigan began at a solution mining facility near Hersey, Michigan in The plant was designed for production of 160,000 tons of Potash per year primarily from a foot thick interval, near the top of the A-1 Evaporite, of relatively pure Potash locally known as the Borgen Bed. The grade of this Potash deposit is one of the highest in the world at nearly 70% KCl by volume. It is also very pure containing negligible Carnallite and about 0.5% insolubles. Potash production at the Hersey mine ceased in 2013 although the facility still does produce Salt (NaCl). In 2008, a significant collection of core from the A-1 Evaporite in the commercial mining area as well as throughout the northern half of Michigan was donated to Western Michigan University. The collection contained over 11,300 linear feet of conventional, 4-inch core sealed in plastic sleeves, from 77 different wells in nine counties. In addition to the cores, several hundred modern wireline logs are available from wells that pass through the Potash zone. Gamma Ray, Compensated Neutron and Lithodensity curves are all useful in defining the stratigraphic occurrence and approximate thickness of the Potash-bearing strata. The Borgen Bed, near the top of the formation is widespread in the western portion of the area, whereas there is a sequence of thinner Sylvite and Sylvite/Halite interbeds in the middle of the formation to the eastern portion of the area. By supplementing the core data with wireline logs, it can be estimated that Michigan s Potash deposits are contained in 17 counties in the central and northern part of the Michigan basin. Based on thickness of Sylvite intervals and grade values from core analysis, it is likely that commercial production can come from nine counties representing 2.9 million acres.

2 References Cited Anderson, R.J., and G.C. Egleson, 1970, Discovery of potash in the A-1 Salina salt in Michigan: in Forum on Geology of Industrial Minerals, Michigan Geological Survey Miscellany 1, p Burgess, R.J., and A.L. Benson, 1969, Exploration for Niagaran reefs in Michigan, Pts. 1-2: Oil and Gas Journal, v. 67/51, p Gill, D., 1977, The Bell River Mills Gas Field; Productive Niagaran Reefs Encased by Sabhka Deposits, Michigan Basin: Michigan Basin Geological Society, Special Paper #2, 118 p. Matthews, R.D., 1970, The distribution of Silurian potash in the Michigan Basin: in Kneller, W.A., ed., Sixth Forum on Geology of Industrial Minerals, Michigan Geological Survey Miscellaneous Paper 1, p Ritter, A.L., 2008, Evaluating the Controls on Reservoir Heterogeneity of Silurian Pinnacle Reefs, Michigan Basin: Thesis (MS), Western Michigan University, Kalamazoo, Michigan, 247 p.

3 Occurrence of Potash-bearing strata (Sylvinite) in the Salina A-1 Evaporite in the Central Michigan Basin Dr. William B. Harrison, III Michigan Geological Repository for Research and Education Michigan Geological Survey Western Michigan University Eastern Section American Association of Petroleum Geologists 2014 Annual Meeting London, Ontario, Canada

4 U.S. Potash Facts Potash (K 2 O) refers to a group of potassium bearing minerals, the most common being potassium chloride (KCl). Potassium (K) is the seventh most common element in the earth's crust, and is found in every cell of plants and animals and is essential to their growth U.S. Production 900,000 tons 2012 production value - $675 million (@$750/ton) 2012 Imports 4,000,000 tons Import Sources Canada 84%, Russia 11% Potash produced in Michigan (recently closed), New Mexico, and Utah. Most production from New Mexico

5 U.S. Potash Demand for Agriculture Tons per sq mile More than Source: USGS US Potash Mining Locations

6 U.S. Potash Production and Consumption Statistics U.S. Potash Production and Consumption Underground Potash Mine in Saskatchewan, Canada Production and Consumption in 1000's Tons 7,000 6,000 5,000 4,000 3,000 2,000 1, Mosaic Michigan Potash Solution Mine Hersey, Osceola Co. Production Sales Imports Exports Apparent Consumption Reported Consumption average Price/Ton Mine Employment Mill Employment Import Reliance

7 Occurrence of Michigan Potash strata Contained exclusively in the Salina A-1 Salt Formation in the Michigan Basin Interbedded as relatively pure Sylvite (KCl) beds within Halite (NaCl) in the upper half of the formation Geographically located in basin center at depths between 7000 and 9000 feet deep Some Potash beds occur in all or parts of 17 counties, but commercial quantities may be limited to about 8 counties

8 Michigan Stratigraphic Column 8usWanasGr Restricted Marine Carbonates interbedded with Evaporites Heglillfa,n engilldl"i (if Marmlql.Mil VI' Guelph 001 lcdq)ort [)Of l.n:iifferentiaied Shallow Marine Shelf Carbonates capped by Reefs Burnt BIidfGr undrtfcrcnti:auhi

9 Distribution of Middle Silurian Environments, Michigan Basin Gill, 1977 ~~~~~=:::::~::~'~.;,'~'n~::~"~.~'::~~~~~~~~~~~~~.. ~~~.. ~:] "'-2,~",," h.. p. "'_1 <'",1). A- I r~m Nj~ r.".. GO Lockport ~ ale e",f Dar,ier Clio' on ~'~'~.~.~.n~. 1\_1 ~~~~~~~~::~~~~~:=-'"l Pi,.".. d., RL..."f,; -:~~~~~-r~~~ '''~&~u~p~ and ljl<:herms EdYI! Area of Shoal I Development '~~:::~=====-;,;~ Sltd r ; (".'1rhon:IIP R:lnk Environments o f Niagaran SaJimenl alion ~ Ritter, 2008 S I ~ llmpo;rnne "nd Dnlomitp G~~ ~:~ Anhydrite D~ _ Ni.. y..'" Group Reefal Dolomite

10 Historic Studies of Michigan Potash Dow Chemical Co. research group in late 1966 sampled core in Dow Chemical #8 Salt Well in Midland Co. Compared it to the Gamma Ray log of the Pure- Merton-Emery #1 well 11.4 miles to the SW Matthews, 1970 and Matthews and Egleson, 1973 mapped the distribution of Potash in the A-1 Salt using wireline logs and brine analyses Matthews, 1970 suggested that Potash occurred in parts of 22 counties covering over 13,000 sq. mi. (over 8,000,000 acres) Elowski, 1980, most recent overview From Matthews, 1970 From Anderson and Egleson, 1970

11 Wells that Penetrate the A-1 Salt In the Michigan Basin WEl l SYMBOLS t,.; ~~"PO"'-Wm o..;wti (lil> CondEl"lsiIIe (la;~ion w.l (la; SrOl'llgot "* o L003lioo "'.~~- Only " 0 N3tonI9me~5 coo.,.,., ctlst l'"oillion (r«ijiis mnogot) Qil w..y OtIer h~ion Wei #b~d(las WeI MILES ??<la 4<1R!1 nlv 00 7'15 KI LOMETERS 5034 wells in data set

12 Structural Contour Map on top of Salina A-1 Salt Formation Depths in Subsea W Ell. S"YJr0480LS,(. BRINE [)SPOSAl WELL <).,"" GasWtD Gas Condtl'l""4 t Ou ~ecooowei Gas Sklrage.. *" Gas Sklrage Obsew.lion ". o Loeaicn Only ""0 Han BriM 8Z5 Ob_io:r> (I'IOI~S3l0~) auld "". Odler hjdon WeI.It>iIldoned GAS WEll o MILES KILOMETERS 37.$ e, 24 i. ~ - :-_T-.". -.""""...Un&I ~

13 General Geographic area of occurrence of Potash Beds in Michigan Basin 17 Counties Estimated areal extent of Potash Beds Estimated area with Commercial Potential Roughly 8 Counties 4,600 sq.mi. 2.9 million acres

14 Boreholes with Wireline logs useful for assessing occurrence of Potash Beds o MILES 10 f " KILOMETERS

15 Stratigraphic Occurrence of Potash Potash is present in two distinct portions of the A- 1 Salt Borgen Bed Thick (up to 30 ft.) of relatively pure Sylvite, near the top of the formation Basin-Centered Beds several to numerous thinner and slightly lower grade Sylvite in the middle or upper third of the formation Beds in Salina A-1 Salt Salina A-1 Carbonate Salina A-1 Salt Borgen Bed Basin-Centered Beds Niagaran Carbonate

16 NW to SE Cross Section Through NW Potash Bearing Zone SE A-2 Salt A-1 Carbonate Michigan boreholes with Wireline logs Borgen Bed Basin Centered Beds NW A-1 Salt Brown Niagaran SE

17 A-1 Salt Core Collection In 2008 the entire core collection from Mosaic Corp. (previously drilled by PPG and IMC) was transferred to Western Michigan University. Total of 77 wells comprising 11,380 feet of cored material Cores sealed in poly bags and untouched since initial coring and sampling for analyses

18 Park # 1-12 Core Showing Primary Depositional Layering in Halite

19 Sylvite occurrence in the A-1 Salt May be as pure Sylvite beds interbedded with Halite or as intimately intermixed halite and Sylvite crystals in the same bed Visual estimation of Sylvite and Halite percentages can be made on exterior of core due to the relative difference in solubility of the two minerals during the coring process with Halite saturated drilling fluid

20 Assay Analysis of Potash Grade Some samples of split core portion (1/4 or 1/8) of whole core Most samples were from powder drilled from fresh core surface in the interior of a split core Half meter to one meter sampled continuously

21 Quality Control on Analyses Replicate and duplicate samples were analyzed Solid core chunks as well as drilled powder samples from the same interval were compared

22 Potash from Borgen Bed Interval A-1 Carb A-1 Salt Borgen Bed Basin-Centered Beds GR PEF RHOB NPHI KCl +NaCl NaCl KCl Visual Volume estimate: This foot long piece of core averages approximately 52.1% KCl or 32.4% K 2 O (Average Borgen Bed assay is 58.7% KCl) :50% KCl+NaCl % - NaCl :50% - KCl+NaCl % - KCl :50% KCl+NaCl % - KCl % - NaCl 0.00 KCl +NaCl B. Niag Willmet-Gray #1-31 Osceola Co N-8W P#35800 A-1 Evap Core: ft KCl NaCl Cored interval shown:

23 Portion of Core through Basin- Centered Beds in Osceola County GR PEF NPHI RHOB Visual Volume Estimate: This eight inch piece is approximately 37.5% KCl or 23.7% K 2 O 1-50:50% KCl+NaCl % - KCl % - NaCl :50% KCl+NaCl % - KCl % - NaCl 0.00 KCl +NaCl KCl NaCl KCl +NaCl KCl NaCl

24 General Geographic area of occurrence of Potash Beds in Michigan Basin 17 Counties Estimated areal extent of Potash Beds Estimated area with Commercial Potential Roughly 8 Counties 4,600 sq.mi. 2.9 million acres

25 Summary of Michigan Potash Occurs only in the Salina A-1 Salt in the center of Michigan basin, 8 counties have thickest, many areas may have recoverable deposits Missaukee, Roscommon, Clare, Osceola, Gladwin, Midland, Isabella, Mecosta (Approximately 2,900,000 gross acres) Two main target horizons Estimated through volumetric observations of %KCL Borgen Bed - Generally one continuous bed 10 to 30 feet thick, Average estimated volume calculation from core observation: 55% KCL or 35% K 2 O Primarily NW side of Basin Basin-Centered Beds Numerous thin beds (inches to a few feet thick) gross interval 70 to 150 feet thick, net log measured potash thickness feet Average estimated volume calculation from core observation: 43.8% KCL or 27.7% K 2 0 Comparison to other world potash production grades Canada 18% 24% K 2 0 Utah 24% K 2 0 New Mexico 8% - 22% K 2 0 Russia 18% - 22% K 2 0